* {
    margin: 0;
    padding: 0;
    list-style: none;
    text-decoration: none;
}

@function vw($vw) {
    @return $vw / 750 * 100+vw;
}
body{
    background: url(../img/bg.png) no-repeat;
    background-size: vw(750) vw(1200);
}